The failure of the anti-skid system always increases the minimum landing distance or RTO distance, regardless of the runway condition. Which leaves the only possible answer: at least doubles the minimum braking distance on a dry runway.

The auto-brake system can be used for automated braking during landing or during a rejected take-off (RTO). There are several modes the auto-brakes can be in:

Off

Armed the auto-brake system is ready to be used but there are conditions which have to be met before the auto-brakes start operating.

Activated When the system was armed and the necessary conditions have been met the system can be activated in different ways depending on the type of aircraft.

The auto-brake system is not useable when the alternate braking system is in use. Depending on the type of aircraft, 3 to 5 modes of deceleration can be selected. Anti-skid protection is provided during autobrake operation, with inoperative anti-skid the auto-brake system will not operate. The autobrakes will be armed once a deceleration mode has been selected. When the aircraft touches down and the main wheels spin up or by the means of weight on wheels the auto-land system will be activated. The auto-land system continues to brake until a complete stop or until the auto-brakes are disarmed.

The selected deceleration mode will give a standard deceleration rate independent on the weight of the aircraft for a dry runway.

Disarming of the autobrakes will occur by any of the following crew actions:

• Manual braking
• Advancing any thrust lever after landing
• Moving the speed brake lever to down after speed brakes have been deployed on the ground.
• Moving the autobrake selector to Disarm or Off.

When RTO is selected, the maximum brake pressure will be applied when all thrust levers a closed above a ground speed of 85 knots. So below this 85 knots the autobrakes are not activated.